Robustness of the round-robin differential-phase-shift quantum-key-distribution protocol against source flaws

Abstract

Recently, a new type of quantum key distribution, called the round-robin differential-phase-shift (RRDPS) protocol [T. Sasaki et al., Nature (London) 509, 475 (2014)], was proposed, where the security can be guaranteed without monitoring any statistics. In this Rapid Communication, we investigate source imperfections and side-channel attacks on the source of this protocol. We show that only three assumptions are needed for the security, and no detailed characterizations of the source or the side-channel attacks are needed. This high robustness is another striking advantage of the RRDPS protocol over other protocols.